Control device of internal combustion engine

Abstract

When either one of two injectors of each cylinder becomes abnormal, a control device performs failsafe control of performing increase correction of injection quantity of a normal injector. If actual injection quantity is restricted with the maximum injection quantity that can be injected by the normal injector during the execution of the failsafe control, the control device restricts duty of an actuator of an intake air quantity adjustment mechanism (such as a throttle opening degree), thereby restricting intake air quantity to intake air quantity that does not cause melting damage of a catalyst. Thus, increase of deviation of an air-fuel ratio toward a lean side can be inhibited, and the melting damage of the catalyst can be prevented.

1. A control device of an internal combustion engine having a plurality of injectors provided on an intake side of each of a plurality of cylinders of the internal combustion engine, the control device comprising:
 an abnormality diagnosis means for specifying an abnormal injector when either one of the plurality of injectors of either one of the cylinders becomes abnormal; and 
 a failsafe control means for performing failsafe control of prohibiting an injection operation of the injector specified to be abnormal by the abnormality diagnosis means and of performing increase correction of injection quantity of a normal injector such that fuel quantity equivalent to request injection quantity is injected only by the normal injector, wherein 
 the failsafe control means restricts intake air quantity when the request injection quantity exceeds the maximum injection quantity that can be injected by the normal injector during execution of the failsafe control. 
 
   
   
     2. The control device as in  claim 1 , wherein
 the failsafe control means restricts the intake air quantity by restricting at least one of a throttle opening degree, an intake valve lift amount, intake valve timing, an EGR valve opening degree and an airflow control valve with a guard value. 
 
   
   
     3. The control device as in  claim 2 , further comprising:
 an airflow meter for sensing the intake air quantity, wherein 
 the failsafe control means performs feedback control of at least one of the throttle opening degree, the intake valve lift amount, the intake valve timing, the EGR valve opening degree and the airflow control valve such that a sensing value of the airflow meter coincides with a target restriction value when the failsafe control means restricts the intake air quantity. 
 
   
   
     4. The control device as in  claim 2 , further comprising:
 an airflow meter for sensing the intake air quantity, wherein 
 the failsafe control means performs feedback control of at least one of the throttle opening degree, the intake valve lift amount, the intake valve timing, the EGR valve opening degree and the airflow control valve such that correction air quantity obtained by applying phase lead correction to a sensing value of the airflow meter coincides with a target restriction value when the failsafe control means restricts the intake air quantity. 
 
   
   
     5. The control device as in  claim 2 , further comprising:
 an intake pipe pressure sensor for sensing intake pipe pressure, wherein 
 the failsafe control means performs feedback control of at least one of the throttle opening degree, the intake valve lift amount, the intake valve timing, the EGR valve opening degree and the airflow control valve such that a sensing value of the intake pipe pressure sensor coincides with a target restriction value when the failsafe control means restricts the intake air quantity. 
 
   
   
     6. The control device as in  claim 1 , wherein the internal combustion engine is configured to be able to set the request injection quantity greater than the maximum injection quantity of the single injector. 
   
   
     7. A method of controlling an internal combustion engine having a plurality of injectors provided on an intake side of each of a plurality of cylinders of the internal combustion engine, the method comprising:
 specifying an abnormal injector when either one of the plurality of injectors of either one of the cylinders becomes abnormal; and 
 performing failsafe control of prohibiting an injection operation of the injector specified to be abnormal and of performing increase correction of injection quantity of a normal injector such that fuel quantity equivalent to request injection quantity is injected only by the normal injector, wherein 
 performing the failsafe control includes restricting intake air quantity when the request injection quantity exceeds the maximum injection quantity that can be injected by the normal injector during execution of the failsafe control. 
 
   
   
     8. The method as in  claim 7 , wherein
 performing the failsafe control includes restricting the intake air quantity by restricting at least one of a throttle opening degree, an intake valve lift amount, intake valve timing, an EGR valve opening degree and an airflow control valve with a guard value. 
 
   
   
     9. The method as in  claim 8 , further comprising:
 sensing the intake air quantity using an airflow meter, wherein 
 performing the failsafe control includes performing feedback control of at least one of the throttle opening degree, the intake valve lift amount, the intake valve timing, the EGR valve opening degree and the airflow control valve such that a sensing value of the airflow meter coincides with a target restriction value when the failsafe control restricts the intake air quantity. 
 
   
   
     10. The method as in  claim 8 , further comprising:
 sensing the intake air quantity using an airflow meter, wherein 
 performing the failsafe control includes performing feedback control of at least one of the throttle opening degree, the intake valve lift amount, the intake valve timing, the EGR valve opening degree and the airflow control valve such that correction air quantity obtained by applying phase lead correction to a sensing value of the airflow meter coincides with a target restriction value when the failsafe control restricts the intake air quantity. 
 
   
   
     11. The method as in  claim 8 , further comprising:
 sensing intake pipe pressure using an intake pipe pressure sensor, wherein 
 performing the failsafe control includes performing feedback control of at least one of the throttle opening degree, the intake valve lift amount, the intake valve timing, the EGR valve opening degree and the airflow control valve such that a sensing value of the intake pipe pressure sensor coincides with a target restriction value when the failsafe control restricts the intake air quantity. 
 
   
   
     12. The method as in  claim 7 , wherein the internal combustion engine sets the request injection quantity greater than the maximum injection quantity of the single injector.